Technological development for reducing shrinkage cracking in cold climates

针对低温条件下抑制收缩开裂的技术发展，研究了减缩剂的冻害降解机理和干缩减缩效果，开发了一种抗冻融性能提高的新型减缩剂（SRA）。此外，根据冻融作用变质和干燥收缩的综合模型，对减缩剂的分子结构进行了优化。在实验室中，我们检测了新鲜混凝土和硬化混凝土的性能，如和易性、凝结性、力学性能、干燥收缩率、碳化、钢筋腐蚀和抗冻融性，并确认SRA混凝土的性能与未SRA混凝土的性能相当。最后，我们还在预拌混凝土厂生产了SRA混凝土，并在实际结构中进行了制作，确认了SRA混凝土的性能满足目标要求。

For technological development of shrinkage cracking suppression in cold climates, we have elucidated the frost damage degradation mechanisms and drying shrinkage reduction of shrinkage reducing agent, and developed a new shrinkage reducing agent (SRA) with improved freeze-thaw resistance. In addition, our shrinkage reducing agents had been optimized the molecular structure of shrinkage reducing agent according to an integrated model for the freezing and thawing action deterioration and drying shrinkage. In laboratory we examined the properties of fresh and hardened concrete such as workability, setting, mechanical properties, drying shrinkage, carbonation, rebar corrosion and the freeze-thaw resistance, and confirmed that the properties of SRA concrete were equivalent to those of concrete without SRA. Finally, we had also manufactured SRA concrete at ready-mixed concrete plant and fabricated in the actual structures, and confirmed that the performance of SRA concretes satisfied the target requirements.